The Association of Secondary Teachers Ireland (ASTI) has told its members they won't be compelled to work to help prepare students in the weeks ahead of the rescheduled Leaving Cert.
The union issued a clarification to members over the weekend to correct "a considerable amount of misinformation".
Teachers are being asked to return to the classroom for at least two weeks to help the 61,000 Leaving Cert candidates entered for the exam, now pencilled in for an end of July/ early August start.
The Department of Education is also hoping teachers would maintain contact with these students in the period before the two weeks back in the classroom. The ASTI has told its members the department is worried about maintenance of motivation and engagement of students.
This would mean teachers staying in touch with students in June/early July, when they are normally not teaching.
However, while schools close for tuition at the end of May, the 13 days given over to exams are part of the official school year.
The two second-level teacher unions, the ASTI and the Teachers' Union of Ireland (TUI), support the rescheduling of the Leaving Cert and said they were committed to serving the best interests of students.
According to ASTI president Deirdre McDonald, at a meeting of its leadership held remotely on Friday evening after the postponement announcement by Education Minister Joe McHugh, concerns were raised about a number of issues including provision for students with special needs, social spacing at practical exams and the requirement for people to finish projects that are locked in schools.
And an ASTI spokesperson said there was a considerable amount of confusion on social media about the issue of working.
"For the record, contrary to misinformation that is circulating, no teacher will be required to do anything. The proposal from the Department of Education and Skills cannot be enforced," the ASTI states in its clarification.
Issues raised by members include the position of those with an underlying medical condition being asked to return to the classroom and of non-permanent teachers whose contracts finish at the end of May.
The State Examinations Commission will announce a timetable for exams in June, based on the medical advice at the time.
Apart from the start date, the big question is whether it will be possible to run more than one exam per day.
With more than 30 subjects, on the basis of only one exam per day, it could take four weeks to complete the schedule.
The Junior Cycle June exams have been cancelled and will take place in schools early in the next academic year.
For years, the Junior Cycle exams have been the source of tension between the Department of Education and the ASTI, which has resisted moves to switch to a school-based system.
Among the issues to be decided in relation to these exams is who would supervise and correct them.